
package com.dream.launcher;

import android.app.WallpaperManager;
import android.content.Context;
import android.os.IBinder;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;

public class Workspace extends ViewGroup {
    @SuppressWarnings({"UnusedDeclaration"})
    private String TAG = "workspace";

    private Scroller mScroller;
    private VelocityTracker mVelocityTracker;
    private static final int SNAP_VELOCITY = 600;
    private float mLastMotionX;
    private float mLastMotionY;
    private int mTouchSlop;
    
    private int mTouchState = TOUCH_STATE_REST;
    private final static int TOUCH_STATE_REST = 0;
    private final static int TOUCH_STATE_SCROLLING = 1;

    private int mCurScreen;

    private final WallpaperManager mWallpaperManager;
    private boolean mFirstLayout = true;

    private ScreenIndicator mScreenIndicator;
    
    public Workspace(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }
    
    public Workspace(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mWallpaperManager = WallpaperManager.getInstance(context);
        mScroller = new Scroller(context);
        mCurScreen = 1;
        mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
        Log.d(TAG, "~~~mTouchSlop~~~  " + mTouchSlop);
    }
    
    public void setScreenIndicator(ScreenIndicator indicator)
    {
        mScreenIndicator = indicator;
        initScreenIndicator();
    }
    
    private void initScreenIndicator()
    {
        mScreenIndicator.update(getChildCount(), mCurScreen + 1);
    }


    public void snapToDestination() {
        final int screenWidth = getWidth();
        final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
        snapToScreen(destScreen);
    }

    public void snapToScreen(int whichScreen) {
        // get the valid layout page
        whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
        if (getScrollX() != (whichScreen * getWidth())) {

            final int delta = whichScreen * getWidth() - getScrollX();
            mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2);
            mCurScreen = whichScreen;
            invalidate();
            // Redraw the layout
        }
        initScreenIndicator();
        updateWallpaperOffset();
    }

    public void setToScreen(int whichScreen) {
        whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
        mCurScreen = whichScreen;
        scrollTo(whichScreen * getWidth(), 0);
        initScreenIndicator();
        updateWallpaperOffset();
    }

    public int getCurScreen() {
        return mCurScreen;
    }

    @Override
    public void computeScroll() {
        // TODO Auto-generated method stub
        if (mScroller.computeScrollOffset()) {
            scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
            postInvalidate();
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG, "~~~onTouchEvent~~~");
        if (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        }
        mVelocityTracker.addMovement(event);
        final int action = event.getAction();
        final float x = event.getX();
        final float y = event.getY();
        switch (action & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN:
                if (!mScroller.isFinished()) {
                    mScroller.abortAnimation();
                }
                mLastMotionX = event.getX();
                break;
            case MotionEvent.ACTION_MOVE:
                int deltaX = (int) (mLastMotionX - x);
                mLastMotionX = x;
                Log.d(TAG, "~~~onTouchEvent~~~ ACTION_MOVE ~~~ deltaX~~~" + deltaX);
                scrollBy(deltaX, 0);
                break;
            case MotionEvent.ACTION_UP:
                final VelocityTracker velocityTracker = mVelocityTracker;
                velocityTracker.computeCurrentVelocity(1000);
                int velocityX = (int) velocityTracker.getXVelocity();
                Log.d(TAG, "~~~onTouchEvent~~~ ACTION_UP ~~~ velocityX~~~" + velocityX);
                if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
                    snapToScreen(mCurScreen - 1);
                } else if (velocityX < -SNAP_VELOCITY && mCurScreen < getChildCount() - 1) {
                    snapToScreen(mCurScreen + 1);
                } else {
                    snapToDestination();
                }
                if (mVelocityTracker != null) {
                    mVelocityTracker.recycle();
                    mVelocityTracker = null;
                }
                mTouchState = TOUCH_STATE_REST;
                break;
            case MotionEvent.ACTION_CANCEL:
                mTouchState = TOUCH_STATE_REST;
                break;
        }

        return true;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        Log.d(TAG, "~~~onInterceptTouchEvent~~~");
        final int action = ev.getAction();
        if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) {
            return true;
        }
        final float x = ev.getX();
        final float y = ev.getY();
        switch (action) {
            case MotionEvent.ACTION_MOVE:
                final int xDiff = (int) Math.abs(mLastMotionX - x);
                if (xDiff > mTouchSlop) {
                    mTouchState = TOUCH_STATE_SCROLLING;
                }
                Log.d(TAG, "~~~onInterceptTouchEvent~~~ACTION_MOVE~~~  xDiff " + xDiff);
                Log.d(TAG, "~~~onInterceptTouchEvent~~~ACTION_MOVE~~~  mTouchState  " + (mTouchState == TOUCH_STATE_SCROLLING?"scrolling":"reset"));
                break;
            case MotionEvent.ACTION_DOWN:
                mLastMotionX = x;
                mLastMotionY = y;
                mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
                Log.d(TAG, "~~~onInterceptTouchEvent~~~ACTION_DOWN~~~  mTouchState  " + (mTouchState == TOUCH_STATE_SCROLLING?"scrolling":"reset"));
                break;
            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
        }
        return mTouchState != TOUCH_STATE_REST;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Log.d(TAG, "~~~onMeasure~~~");
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        final int width = MeasureSpec.getSize(widthMeasureSpec);
        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        if (widthMode != MeasureSpec.EXACTLY) {
            throw new IllegalStateException("Workspace can only be used in EXACTLY mode.");
        }

        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        if (heightMode != MeasureSpec.EXACTLY) {
            throw new IllegalStateException("Workspace can only be used in EXACTLY mode.");
        }

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
        }

        scrollTo(mCurScreen * width, 0);
        
        if(mFirstLayout){
            updateWallpaperOffset(width * (getChildCount() - 1));
            mFirstLayout = false;
        }
    }
    
    private void updateWallpaperOffset() {
        updateWallpaperOffset(getChildAt(getChildCount() - 1).getRight() - (getRight() - getLeft()));
    }
    
    private void updateWallpaperOffset(int scrollRange) {
        IBinder token = getWindowToken();
        if (token != null) {
            mWallpaperManager.setWallpaperOffsetSteps(1.0f / (getChildCount() - 1), 0 );
            mWallpaperManager.setWallpaperOffsets(getWindowToken(),
                    Math.max(0.f, Math.min(getScrollX()/(float)scrollRange, 1.f)), 0);
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        Log.d(TAG, "~~~onLayout~~~");
        int childLeft = 0;
        int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View childView = getChildAt(i);
            if (childView.getVisibility() != View.GONE) {
                final int childWidth = childView.getMeasuredWidth();
                childView.layout(childLeft, 0, childLeft + childWidth,
                        childView.getMeasuredHeight());
                childLeft += childWidth;
            }
        }
    }

}
